This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Myostatin is a protein found in muscle and blood. Myostatin concentration regulates the amount of muscle mass in humans and animals. Myostatin concentration, will be analyzed shortly after an exercise bout (acute) as well as at the end of the training program (chronic). In order to reverse or inhibit the effects of elevated myostatin, it is important to explore the different possible mechanistic pathways that might exist to favorably alter myostatin's role in regulating muscle mass.